Fuel system pressure modulator



June 19, 1962 E. M. BROHL FUEL. SYSTEM PRESSURE MODULATOR 2 Sheets-Sheet 1 MAN/F10 VACUUM C'ARBUPETOR ATTORNEY June 19, 1962 E. MQBROHL 3,039,485

FUEL SYSTEM PRESSURE MODULATOR 2 Sheets-Sheet 2 Filed Sept. 25, 1957 6i Q h INVENTOR k dozJ/Wfizarf/ lillll Ill-W BY f V I /v 12,811 fl- ArmQ/vz United States Patent 3,039,485 FUEL SYSTEM PRESSURE MODULATOR Earl M. Brohl, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Sept. 23, 1957, Ser. No. 685,566 1 Claim. (Cl. 137483) The present device relates to a mechanism for regulating the pressure in the fuel system of an internal combustion engine in proportion to the load on the latter.

In the present device fuel is adapted to be supplied under pressure from a fuel source to a carburetor but which pressure is made to vary in accordance with engine load as manifested by manifold vacuum, and further which pressure varies directly with load. In providing a mechanism whereby the fuel is supplied under pressure to the carburetor a number of advantages ensue including a decreased tendency of vapor lock, increased fuel economy and improved engine performance particularly under conditions of acceleration.

While previous fuel systems have been employed in which fuel is supplied to a carburetor device under pressure, applicant has provided a unique pressure controlling mechanism which insures that such pressure will correspond more nearly to the load requirements of the engine, and further which device is of simple and inexpensive construction.

It is a further object of the present invention to uniquely combine the subject pressure regulating mechanism with a fuel filtering mechanism in a way which further reduces the cost of the fuel system as well as providing means for conveniently venting the system at a point where fuel vapors tend to occur due to the turbulence which frequently accompanies filtering of fuel.

The details of the present invention as well as other objects and advantages are set forth in the description which follows.

In the drawings:

FIGURE 1 is a partially sectioned elevational view along line 11 of FIGURE 2 showing a fuel filter embodying the subject invention;

FIGURE 2 is a plan view of FIGURE 1',

FIGURE 2a is a view along line 2a-2a of FIGURE 2.

FIGURE 3 is a sectional View along lines 33 of FIGURE 2; and

FIGURE 4 is a modified form of the invention.

Referring to FIGURE 1 a relatively high pressure pump draws fuel from a tank or reservoir 12 and is adapted to supply the same through a conduit 14 to pressure modulator-filter device 16 from which fuel is supplied through a conduit 18 to a carburetor 20. Vehicle underhood temperatures are continually increasing which, coupled with the use of higher volatility fuels, has greatly increased the tendency of the fuel to boil or vaporize. These factors have increased the propensity toward vapor lock formation within the fuel system. Accordingly, it is desirable to increase the pressure under which the fuel is maintained to reduce the tendency of the latter to vaporize. Pressurization of the fuel also increases the overall engine performance by improving acceleration, maintaining a more nearly constant air-fuel mixture ratio, and generally improving gasoline economy.

Rather than maintaining a constantly high pressure, it is found to be more desirable to provide means for modulating the fuel pressure in accordance with engine load. In other words, when the engine is under a heavy load it is desirable to have the fuel under a maximum pressure to insure the requisite fuel flow. On the other hand, under light engine load conditions it is unnecessary and uneconomical to maintain the fuel under a high pressure.

Accordingly, the fuel pressure regulator portion 22 of 3,039,485 Patented June 19, 1962 the device 16 includes a first casing member 24 having fuel inlet and outlet passages 26 and 28. Casing 24 is centrally bored to provide a pair of chambers 30 and 32 separated by a wall 34. The fuel inlet passage 26 communicates with upper chamber 30 which in turn communicates through a port or passage 36 with a chamber 38 recessed in the upper face of casing 24.

Inlet passage 26 also communicates with the chamber 38 through a restricted passage 40 providing a parallel fuel flow path with respect to passage 36. As seen in FIGURE 3, casing 24 also includes a vertically extending or longitudinal passage 42 communicating at its upper end with chamber 38.

The lower end of longitudinal passage 42 communicates with a filter inlet chamber 46 formed by a filter cover 48 and a recessed portion 50 formed in the lower face of casing 24. An annular shoulder 52 is formed at the bottom edge of casing chamber 32 and upon which the filter cover 48 is adapted to seat. Cover 48 includes a collar portion 54 extending partially within casing chamber 32 and which collar suitably supports an O-ring 56 to provide a fluid tight seal between chambers 32 and 46. Thus, fuel from longitudinal passage 42 flows into filter inlet chamber 46 and outwardly therefrom through a plurality of ports 58 formed in filter cover 48.

The bottom Wall of casing 24 includes an annular shoulder 60 upon which the conventional glass type filter bowl 62 is mounted through a gasket 64 by a conventional locking mechanism indicated generally at 66. The bottom surface of filter cover 48 has an annular edge 68 formed thereon to which a conventional U-shaped annular filter member 70 is bonded. Filter member 70 is radially inwardly spaced from cover 62 to provide an annular space 72 from which the fuel may flow radially inwardly through the filter, as shown by arrows, to be purified. The clean fuel will then flow upwardly through collar 54, chamber 32, to casing outlet passage 28 passing through conduit 18 to the carburetor 20.

As already noted, the fuel from pump 10 is under pressure, the value of which will be varied by that part of regulator 22 now to be considered. Regulator 22 includes a diaphragm 74 peripherally clamped between casing 24 and a cover casing 76. A valve member 78 is centrally fixed to diaphragm 74 for movement therewith. Valve member 78 includes a stud portion 80 which terminates in a frusto-conical portion 82 adapted to coact with fuel passage 36 which is correspondingly tapered. An annular seat 84 is formed within casing chamber 38 and is adapted to provide a seat or stop for the diaphragm 74. A spring member 86 is disposed within a chamber 88 formed in cover casing 76 and is adapted to bias the diaphragm member against the annular seat 84. In order to prevent undue wear on diaphragm 74 suitable reinforcing washers 90 are clamped on either side of the diaphragm and are adapted to respectively cooperate. with the seat 84 and the spring 86. Annular seat 84 includes one or more openings 92 therein to insure that the seat in no way interferes with fuel flow through chamber 38 for reasons to be subsequently considered.

Chamber 88 includes a port 94 which communicates with a conduit 96 the other end of which is suitably connected to the inlet manifold, not shown.

Under heavy load conditions the manifold vacuum will be sufficiently low to insure that spring 86 will cause the diaphragm 74 to rest upon annular seat 84 causing maximum opening of valve portion 82 and permitting fuel from the inlet passage 26 to flow around the valve through passage 36 insuring the maximum quantity of pressurized fuel flow to the carburetor 20. Under conditions of light load, the manifold vacuum in chamber 88 will be sufficient to overcome the force of spring 86 causing the diaphragm to be moved upwardly seating the frusto-conical 3 valve portion 82 within passage 36 limiting the flow of fuel to that amount which can pass through restricted passage 40.

Under idling or light load conditions with valve 78 closed, the flow of fuel through regulator 22 is limited by the capacity of restricted passage 40. The size of passage 40 is determined by the needs of a particular engine idling or light load operation. The restricted nature of passage 40 in addition to limiting the quantity of fuel flow also reduces the fuel pressure which is compatible with light load conditions.

The manifold vacuum in chamber 88 may vary between maximum and minimum values under which conditions the valve element 78 will modulate the quantity of fuel flowing through passage 36 in accordance with engine load requirements.

Due to certain unavoidable turbulence created by fuel flowing through pressure regulator 22 as well as filter 70, a limited amount of vaporization may take place. To insure that any such vapor within device 16 does not pass on through conduit 18 to the carburetor, a vent is provided. As best seen in FIGURES 2 and 2a, the vapor vent includes a restricted passage 100 formed in casing 24 and communicating With chamber 38. The other end of the vent passage is adapted to communicate with a passage 102 which connects with a conduit 104 returning to reservoir 12. Thus, any vapor formed by heating or agitating the fuel in device 16 is bled off through the calibrated restriction 100 below the diaphragm 74 and returned to the reservoir. The vapor return also serves to further regulate the low pressure at idle by bypassing the excess fuel under conditions of low engine load.

The modification of FIGURE 4 functions in substantially the same manner as that of FIGURES 1 through 3. In this instance a diaphragm controlled valve element 106 includes a fixed fuel restriction or passage 108 to provide the fuel flow under low engine load conditions. In this modification fuel is again supplied from an inlet passage 110 to a chamber 112 whence the fuel flows through radial openings 114 in the filter cover 116 thereafter passing through the filter element 118 to outlet passage 120. Depending on the vehicle load conditions, the valve element 106 Will be positioned between its open and closed position modulating the quantity of fuel supplied as in the modification of FIGURES 13.

The modulated fuel outlet chamber 122 defined by casing 124 and the diaphragm 126 is communicated by a vapor vent restriction 128 to a conduit 130 adapted to return vapors to the fuel reservoir.

I claim:

,A fuel system comprising a pressure regulator including a casing, a fuel inlet chamber in the casing, a conduit passage providing pressurized fuel to said chamber, a fuel outlet chamber, a first passage means communicating said inlet and outlet chambers, valve means for controlling the fuel flow through said first passage means, engine load responsive means for controlling said valve to increase fuel flow with increases in load, a second passage means communicating said inlet and outlet chambers to insure a minimum fuel flow through the regulator irrespective of flow through the first passage means, and an outlet conduit communicating with said fuel outlet chamber, a filter device disposed intermediate said outlet chamber and said outlet conduit, and means for venting fuel vapors from said outlet chamber.

References Cited in the file of this patent UNITED STATES PATENTS 341,776 Shook May 11, 1886 1,148,922 Pagano Aug. 3, 1915 1,487,230 Gaskin Mar. 18, 1924 1,511,163 Heid Oct. 7, 1924 2,254,850 Mallory Sept. 2, 1941 2,599,699 Dilworth et al June 10, 1952 2,633,146 Witt Mar. 31, 1953 2,707,051 Mailhot et al. Apr. 26, 1955 2,737,167 Dickey Mar. 6, 1956 2,774,374 Schneider Dec. 18, 1956 

